A community leader said she was "appalled" after she heard that two teenage girls dropped bricks onto a car in a Suffolk town.
The girls, aged about 13-years-old, were seen on the bridge near the Homebase roundabout on Waldingfield Road at about 4.45pm on Friday, February 3.
An object, believed to be a brick or a rock, hit a car windscreen, causing it to crack.
Sudbury town mayor Ellen Murphy said: "It is extremely dangerous. We have seen examples where rocks have come off bridges and caused fatalities.
"They don't know the risks. What if there was children in the car? It is not just the car that they hit but the other cars on the road as well."
The girls have been described as both having light hair and wearing green blazers.
Ms Murphy said the children need to be shown what the consequences of the actions could be and said officers could visit schools to talk to the children.
She added: "I do think it is important that parents know where there children are at any given time, especially now given that it is half term.
"How else are you going to stop it? Schools could warn the children over the dangers of this, but the children obviously see this as a laugh. It is not funny.
"It is risking life. Once a life has gone it is gone and you can't get it back.
"I am appalled. I think they need to be shown by the police examples of when things like this go terribly wrong.
"Show them photographs. I know there was a lot about an incident on the M11 and I think the police should show children examples and what the consequences are."
Anyone with any information is being askeed to conact Suffolk police quoting the crime reference number 37/7062/23.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules here